Totally agree on the Lux. Id also consider the Leica 90mm Tele-Elmarit-M f/2.8 because its lower micro-contrast and spherical aberration create a softer, more painterly skin texture for portraits.

If you want that classic soul and glow, you gotta go with the Leica 50mm Summilux-M f/1.4 Pre-ASPH. It has this gorgeous rendering wide open that makes skin look amazing without being clinical. The Leica 50mm Summicron-M f/2 Dual Range is a solid, more affordable choice, but the Lux has that specific creaminess you need for lifestyle shots. Its basically the gold standard for vintage character.

Honestly, I am struggling with the exact same thing. I have been eyeing the Leica 75mm Summilux-M f/1.4 Pre-ASPH for portraits, but the reliability issues are terrifying. Balsam separation is a huge risk with these older Canada-made units, and the haze can be permanent if it's etched the glass. It is so frustrating because you want that glow, but the mechanical risks make me so nervous to actually buy one... it is just a total headache.

Basically comes down to the Lux for glow or the 90mm for texture. Adding my two cents... if youre on a budget but want that vintage soul, the Leica 50mm Elmar f/2.8 Collapsible is a hidden gem for portraits. Practical tip: always check for haze or oil on the blades when buying these older M lenses. It can turn character into a muddy mess pretty fast.